Pep Guardiola's all-conquering Barcelona, Real Madrid's three-peaters and the 25 Champions League-winning teams of the 21st century so far - ranked

There is no greater achievement in European football than winning the Champions League. It's an unforgiving tournament that often rewards grit, discipline and courage above all else, and as a result, the team with the best players doesn't always come out on top.

Quite often, one or two of the big names will breeze through the group stage, only to take their eye off the ball for a split second in the knockouts and be sent packing. This is a tournament that demands near-perfection, and any players who cannot cope with that pressure are quickly found out.

Over the past 25 years, Real Madrid have laid down the most solid blueprint for European success, winning eight titles - four more than any other club. Barcelona have lifted the trophy four times compared to Bayern Munich's three, while AC Milan, Chelsea and Liverpool are the only other sides to win it more than once this century.

It means so much because it's the hardest competition to conquer. Any team that reaches the top of the mountain has to be top-class, or at least possess an unbreakable mentally. However, no one Champions League winner is the same as another.

With that in mind, GOAL has ranked all the winners of the 21st century so far, taking into account the degree of difficulty in terms of opponents, quality of performances, entertainment value and just how big a mark they left in the tournament history books...